This application is based on and claims priority to Japanese Patent Application No. 10-114430, which was filed on Apr. 24, 1998.
1. Field of the Invention
The present invention generally relates to an outboard motor for use with a watercraft. More specifically, the present invention relates to a cowling for an outboard motor powered by an internal combustion engine.
2. Description of Related Art
Outboard motors are often powered by internal combustion engines. The engine is typically positioned within an enclosed cowling. The engine is generally vertically arranged, so that a crankshaft thereof may extend downwardly in driving relation with a water propulsion device of the motor, such as a propeller. In order to balance the motor and because of space considerations, the engine is arranged with a crankcase of the engine facing in the direction of a watercraft to which the motor is mounted (i.e., positioned on a front side of the engine), and with the cylinder head positioned on an end of the engine facing away from the watercraft (i.e., positioned on a rear side of the engine).
Air must be supplied to the engine through the cowling for combustion. Conventionally, the cowling is divided into an engine compartment and an air guide chamber, with an air vent in the cowling communicating with the air guide chamber. Outside air is supplied to the engine through the air vent and air guide chamber. In order to prevent the direct entry of water through the air vent into the intake system, the air vent is positioned away from the intake system, typically in the end of the engine facing away from the watercraft.
In order to adjust the amount of air that flows into the engine, the engine typically includes a throttle device. However, when water splashes into the air vent, it can flow through the air guide chamber and deposit on the throttle body, often resulting in malfunctioning of and/or damage to the throttle device. In addition, during watercraft turns, any water that pools on the flywheel cover can often drain onto the throttle body.
A need therefore exists for a cowling arrangement of an outboard motor which permits the engine to draw sufficient quantities of fresh air, but which prevents the impingement of water on the throttle body desired.
In accordance with the present invention, there is provided a cowling arrangement for an outboard motor powered by an internal combustion engine. The motor is preferably of the type in which the engine is positioned within an engine compartment defined by the cowling. The engine has a top end and a bottom end and a generally vertically oriented crankshaft extending in driving relationship with a water propulsion device of the motor. The cowling arrangement allows large quantities of fresh air for engine combustion while significantly reducing the amount of water which contacts the throttle body.
In a preferred embodiment, the cowling includes a flywheel cover which substantially covers the upper surface of the flywheel and engine. A rib is formed in a portion of the flywheel cover near the throttle body. This rib extends upwards and prevents water splashing into the engine compartment from splashing on the throttle body. Moreover, this rib redirects air passing over the flywheel cover near the throttle body, acting as a labyrinth, which tends to remove water suspended in the air which passes over the throttle body. In addition, a downwardly extending rib extending from the cowling towards the flywheel cover further prevents splashing of water and further redirects the air flowing towards the throttle body.
If desired, a gutter can be formed in the flywheel cover. The gutter provides a channel for draining water off the flywheel cover, thereby preventing pooled water from draining on the throttle body during watercraft turns. In addition, where air guide chamber is narrow, such as where there is little separation between the flywheel cover and the cowling, the addition of a gutter to the flywheel cover can significantly increase the effective height of the rib, thereby permitting more water to be removed from the air before it passes over the throttle body.
In another preferred embodiment, the rib extending downward from the cowling is formed in a continuous L-shape, which further reduces the possibility that splashing water will contact the throttle body, and reduces the chance that water condensing on the dividing wall section of the cowling will subsequently travel over and drip onto the throttle body.
Another aspect of the present invention involves an outboard motor for operating in a body of water. The motor comprises a cowling having an air intake. An internal combustion engine is positioned within the cowling and includes a generally vertically oriented crankshaft. A flywheel is attached to an upper end of the crankshaft, and at least one throttle device is positioned on a side of the engine to adjust an air volume supplied to the engine. A flywheel cover extends above at least a portion of the flywheel and is positioned between an upper end of the engine and a portion of the cowling. The flywheel cover includes at least one upwardly extending rib that is positioned between the air intake and the throttle device so as to direct water, which enters the cowling through the air intake, away from the throttle device.
Further aspects, features, and advantages of the present invention will become apparent from the detailed description of the preferred embodiments which follow.